As consumer appetite for multimedia content continues to grow, internet service providers are struggling to provide sufficient bandwidth. Although wired solutions, such as T1 lines, digital subscriber lines (DSL), and cable modems, are becoming ubiquitous in urban environments, these systems are presently not available to a significant portion of the population. Moreover, acquisition and installation costs associated with these systems make them less appealing
One system that provides a fixed wireless solution with bandwidth comparable to DSL and cable modem technologies is a mesh network architecture. As described in, for example, commonly owned U.S. patent application Ser. Nos. 12/554,135 and 12/275,282, each of which are incorporated herein by reference in their entirety, a mesh network comprises a plurality of wirelessly connected nodes that communicate data traffic across a wide area. The nodes of a mesh network communicate with one another using radio or microwave communications signals
One of the most effective tools to improve wireless links, such as connections between nodes in a mesh network, is the use of directional antennas. The benefits of directional antennas include higher modulation and longer range; decreased interference susceptibility from external sources; decreased interference to other systems; and increased power due to point-to-point regulations in many countries. Despite these advantages, directional antennas are difficult to employ because they must be precisely aligned with a complementary antenna and/or many mesh networks require 360° coverage.
In those mesh networks where it is desirable to have 360° omnidirectional coverage, a plurality of directional antennas must be employed. Unfortunately, the use of multiple directional antennas in close proximity is difficult to implement, as such systems experience debilitating intra-system interference. Thus, co-located wireless directional antennas are normally assigned to different non-interfering frequencies, or are installed with sufficient physical or spatial isolation to avoid interference. Both of these situations negatively impact performance and/or impose installation challenges.
It would therefore be desirable to design a system comprising multiple, co-located directional antennas that operate on a single frequency without significant intra-system interference.